The joint with ball stud, although having been extensively employed in years for the linkages in automotive vehicles, construction machinery, agricultural machinery, packaging machines, and so on, especially for the linkages in steering/operating systems of automotive vehicles, are needed recently to get further compact or slim in construction, higher in stiffness and easy in assemblage thereof, even with inexpensive in production cost. With the common ball-stud joints, a stud of the ball stud is made with a male or external thread around the plain end thereof. After the stud of the ball stud has passed through any counterpart such as levers, arms and so on to extend above the counterpart, an associated nut having a female thread fits on the male or external thread of the extended stud end whereby the ball stud is connected to the counterpart. Nevertheless, the ball-stud joints especially incorporated in the linkages of the automotive vehicles, since required to assemble them with less expensive cost, are so designed as to fasten the ball stud to the associated counterpart by only means of riveting.
An example of conventional ball-stud joints is shown in FIG. 9. The prior ball-stud joint is envisaged to connect a major body 43 to any counterpart, which could be considered to constitute a first counterpart, including a lever member, arm member and so on through a ball stud 41. To this end, the ball stud 41 has a ball 47 that fits for pivoting movement into a ball socket 50 formed in the major body 43, and also has a rod or stud 45 that extends through a hole 51 in the counterpart 42, which could be considered to constitute a second counterpart, and then comes into engagement by means of riveting an extremity of the stud 45 against the counterpart 42 to joint the ball stud 41 together with the counterpart 42. The stud 45 of the ball stud 41 has a flange 44 that cooperates with the riveted head 46 formed on the plain end of the stud 45 by caulking or riveting to hold the lever member 42 between them. The riveting operation is carried out by hammering or pressing an upper die jig 49 against a lower die jig 48 on which the ball 47 of the ball stud 41 lies, thereby forming the plain end of the stud 45 into the riveted head 46.
Moreover, there is also known a ball-stud joint as shown in FIG. 10. The ball-stud joint is to connect a major body 63 to a counterpart 62 through a ball stud 61 as in the joint illustrated in FIG. 9. A ball 67 of the ball stud 61 fits for pivoting movement into a ball socket 72 formed in the major body 63. A stud 65 extends through a hole 73 in any counterpart 62, followed by coming into connection with the counterpart 62 by riveting a plain end of the stud 65. The stud 65 of the ball stud 61 has a flange 64 that cooperates with the riveted head 66 formed on the plain end of the stud 65 by caulking or riveting to hold the counterpart 62 between them. With the ball stud 61 discussed now, riveting the plain end of the stud 65 is carried out by pressing an upper die jig 69 from above against a lower die jig 68 on which the flange 64 around the stud 65 is carried along an annular shoulder 70, thereby forming the plain end of the stud 65 into the riveted head 66. The stud 65 is made with annular raised portion 74 underneath the flange 64 so as to provide an annular groove 71 between them to hold a dust proof cover, not shown, therein.
A linkage disclosed in, for example Japanese Patent Laid-Open No. 2002-227830 is conventionally known, in which a waterproof boot is first installed between a ball stud and a ball socket prior to fastening a lever to a ball stud to complete a ball-socket joint, and a stud of the ball stud is subjected to riveting with the boot being held between the ball stud and the ball socket, forming a plain end of the stud into an enlarged head. A flanged area around the stud is made in a stepwise construction of relatively large flange and a relatively small flange in such a way that only the large flange is substantially burdened with the load-bearing jig at the time of riveting the stud.
Another connection system of a ball stud to a lever to form a linkage is disclosed in, for example Japanese Patent Laid-Open No. 2002-227828, in which a flanged stud of the ball stud is riveted to form an enlarged head to hold a lever in association with the flange around the stud between them, connecting the lever with the ball stud that fits for pivoting movement into a ball socket. The enlarged head is formed on a plain end of the stud by driving from above a punch against a load-bearing jig, on which a ball of the ball stud lies.
Meanwhile, when connecting any counterpart such as an arm, a lever and so on to a major body with a ball stud where a ball fits into a ball socket in the major body, it is preferable to fasten a ball stud to a counterpart by riveting a stud with a dust proof cover being remained installed over the ball stud.
With the joints of the type illustrated in FIG. 9, nevertheless, it could never be possible to form a riveted head at a plain end of the stud 45 of the ball stud 41 irrespective of any dust proof cover being installed over the ball stud 41, because the ball stud 41 would experience the riveting in a condition the ball 47 lies directly on the lower die jig 48.
With the prior ball-stud joints in FIG. 10 where the ball stud 61 is supported with the lower die jig 68, moreover, the stud 65 is supported with the lower die jig 68 in such a manner that a load-bearing area 70 of the jig 68 comes into engagement with the lower surface 75 of the flange 64 of the ball stud 61. This means that the riveted head 66 could not be formed on a plain end of the stud 65 by hammering with any upper die jig 69, with any dust proof cover being remained installed in the annular groove 71, which is formed to hold the dust proof cover therein.